1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor device using a substrate that has an SOI structure.
2. Description of the Related Art
Instead of silicon wafers that are manufactured by thinly cutting an ingot of a single-crystal semiconductor, semiconductor substrates called silicon-on-insulator (SOI) substrates have been developed, which have a thin single-crystal semiconductor layer over an insulating layer. When transistors that are to be included in an integrated circuit are formed using an SOI substrate, parasitic capacitance between drains of the transistors and the substrate can be reduced, which is considered to be effective in improving operation speed and in reducing the amount of power consumption. Therefore, SOI substrates are expected to be applied to high-performance semiconductor devices such as microprocessors.
As a method for manufacturing SOI substrates, a hydrogen ion implantation separation method is known (for example, see Reference 1: Japanese Published Patent Application No. 2000-124092). The hydrogen ion implantation separation method is a method in which hydrogen ions are implanted into a silicon wafer to form a microbubble layer at a predetermined depth from the surface, the surface into which hydrogen ions are implanted is superposed on another silicon wafer, heat treatment is performed to cause separation using the microbubble layer as a cleavage plane, and a thin silicon layer (SOI layer) is bonded to the other silicon wafer. In addition to the heat treatment for separation of an SOI layer, it is necessary to perform heat treatment in an oxidizing atmosphere to form an oxide layer on the SOI layer, remove the oxide layer, perform heat treatment at 1000° C. to 1300° C. in a reducing atmosphere to increase bonding strength between the bonding surfaces, and recover a damaged layer on the surface of the SOI layer.
On the other hand, a semiconductor device, in which a single-crystal silicon layer is provided on an insulating substrate such as a high heat-resistant glass substrate, is disclosed (see Reference 2: Japanese Published Patent Application No. H11-163363). This semiconductor device has a structure in which the entire surface of a crystallized glass substrate with a strain point of 750° C. or higher is protected by an insulating silicon layer and a single-crystal silicon layer obtained by a hydrogen ion implantation separation method is fixed onto the insulating silicon layer.